This is the second largest (2550 km2) national park in Finland. Altitude ranges from 113 metres to 718 metres; annual precipitation is 400–500 mm and average annual temperature at low altitudes approx. -1°C. A large part of the park is above the forest limit but the park also contains extensive Pinus sylvestris (Scots pine) and Betula pubescens (downy birch) forests and in the southeast Picea obovata (Siberian spruce) forests. The forests are low and open but the numerous grey dead trees both standing and fallen, gnarly pines and open vistas have their own beauty. Tree species diversity is low and most species are easy to identify. P. obovata has a very narrow crown, as do the northern races of P. sylvestris, though less markedly so than the spruce. The narrow crowns increase the efficiency of light interception at the low sun angles1 and reduce snow loads2. Unlike in many other boreal regions, in Fennoscandia a broadleaf tree, B. pubescens, extends beyond the coniferous species in response to the oceanic climate3. At higher elevations B. pubescens is mainly variety pumila (arctic downy birch), which intergrades to var. pubescens at low elevations. Variety pumila has arisen from the hybridization of var. pubescens and (sub-)shrub Betula nana (dwarf birch) 4. Features inherited from B. nana have made this tree-like birch suited for Lapland’s harsh conditions5. Other regions where Betula reaches forest limit include Asia’s east coast (see Shiretoko National Park), the northern Ural, the Himalayas and the Caucasus (see Lagodekhi Strict Nature Reserve); Alaska’s Alnus viridis subsp. sinuata (Sitka alder) stands are ecologically homological, too5.

The park is a popular hiking destination but so large that solitude is guaranteed in more remote parts. Undergrowth is sparse and off-trail hiking generally very easy; there are also plenty of hiking routes. The forests are mostly untouched6 but there were also large-scale fellings up to the 1970s, prior to the establishment of the park7. The park area is also used for reindeer grazing. The wild ancestor of reindeer, now extinct in Finland, was a part of the region’s natural fauna but nowadays the excessive size of the reindeer herds has decimated the lichen cover of the drier forests. Free camping is allowed in more remote areas. There are also free wilderness huts. In July, mosquitoes can be very annoying.